This invention relates to an armature winding for a static, converter-fed electrical induction machine.
Static converter-fed electrical induction machines are customarily designed in the same manner as machines for operation with line current using a star or delta circuit, m=3 phase winding and operated with a 6-pulse converter circuit (usually a three-phase bridge). With high capacities and/or current levels it is normal to subdivide the winding into two three-phase systems offset electrically by 30 degrees, thereby resulting in a 12-pulse operation.
Phase numbers deviating from m=3 are seldom employed. A 4-pulse circuit operated with m=2 or m=4 phase windings are employed, for example, only in small-size electronic motors.
The periodical "Elektrische Energie-Technik" Volume 25, No. 6, 1980, pages 277-281, describes an intermediate circuit static frequency converter with a 5-phase winding asynchronous motor in which the 5 phase windings of the armature winding are connected in a polygonal circuit (ring circuit). In these armature windings, as is the case with normal 3-branch polygonal or star circuits, the individual phase windings are current-bearing sequentially at electrical angle spacings offset respectively by 2/m in time, resulting in a 1 m or 2 m pulse operation.
The possibility of adjusting the armature winding to the current and voltage loads of the controllable semiconductor components of an "electronic commutator" for cyclical feed of the phase windings, e.g., with d.c. current, which exists only to a limited extent in accordance with the fundamental principles, is provided by a modification of the coil wire cross-section and/or, if necessary, by a distribution of the individual phase windings into parallel circuits. Particularly for the increasingly powerful modern electronic components, such as disconnectable thyristors (GTOs), field effect transitors (FETs), bipolar power transistors and similar items, the optimum use of these components can often not be attained by these measures. Accordingly, it will be appreciated that it would be highly desirable to provide an armature winding which makes optimum use of powerful modern electronic components.
It is an object of the present invention to provide an armature winding for an electrical machine.
It is also an object of the present invention to provide an armature winding with a high pulse number.
Another object of the invention is to provide an armature winding for developing a high level of equipment efficiency and good concentricity.